Douwe Jan Joustra
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Since the invention of the box kite by Lawrence Hargrave and the bowed kite by William Eddy, there has been only one man who created a major innovat ion i n unmotor ized flight . Of cour se ever y enthusiastic aviation specialist and kite-fanatic knows more people who were inventive: Otto Lilliënthal, Alexander Graham Bell, and Samuel F. Cody. From the perspective of innovation, though, the invention of Francis M. Rogallo was a real breakthrough.

As early as the 1940s, Rogallo started his experiments with the so-called flexible wing. That was the invention that led us to new kite designs by pioneers like Domina Jalbert and Peter Lynn. This was a systems innovation – in thinking and doing – because everybody assumed that a wing needed to be rigid with some kind of an aerodynamic profile. The real paradigm shift is in the innovative idea that the flexible wing, adjusting itself to the streaming of the air, might be a new perspective. Of course there were more ideas in history from flapping wings, balloons, and parachutes. The flapping wings need too much energy, balloons need additional heat, and parachutes have a wrong lift/drag ratio (L/D <1): they fall instead of flying. Rogallo worked on flying, the upward movement with a lift/drag ratio that gives more lift than drag (L/D >1).

Rogallo did not publish too much in media on his motives and work. There is one article of his published in Ford Times (43-3, 1951). He explains that his passion for kite flyingoriginated from his early youth and always kept him fascinated. He became an engineer in aviation and started to doubt the quality of kite designs throughout history. He describes the quest for a better model:

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